Hydraulic Composition with Improved Wear Properties

ABSTRACT

The present invention relates to methods of lubricating a mechanical device by using a low sulfur lubricating composition that contains a friction modifier and provides improved antiwear performance. The invention further provides the lubricating compositions used therein.

FIELD OF INVENTION

The present invention relates to methods of lubricating a mechanicaldevice by using a lubricating composition that contains a frictionmodifier and supplies improved antiwear performance. The inventionfurther provides the lubricating compositions used therein.

BACKGROUND OF THE INVENTION

It is known to employ a metal containing antiwear agent, such as a zinccontaining antiwear agent, in a lubricating composition suitable for ahydraulic system, circulating oil or another industrial oil. Howeversuch agents may form deposits such as resins, sludge and varnish in thehydraulic system. These deposits impair the performance of the hydraulicsystems by causing valve sticking and unresponsive control.Additionally, the cleaning of these systems is difficult since thedeposits are difficult to remove without mechanical abrasion.

International publication WO96/035765 discloses a lubricatingcomposition with a rust reducing or preventing amount of 0.1 to 3 wt %of a metal synthetic aryl sulfonate and 0.01 to 2 wt % of an aliphaticsuccinic acid or anhydride. Further the use of substitutedpolyisobutylene succinic acid or anhydride derivatives of polyol estersor polyamines are excluded because lubricating compositions that containsaid additive do not exhibit acceptable rust resistance properties.

U.S. Pat. Nos. 4,419,251 and 4,419,252 disclose aqueous lubricants withoil-in-water characteristics containing a dispersant/emulsifier systemand an antiwear/rust inhibiting package.

U.S. Pat. No. 5,262,073 discloses a lubricating composition containing azinc dispersant, 0.3 to 1 wt % of calcium nonyl di-naphthalene syntheticsulfonate detergent and 0.09 to 0.85 wt % of calcium alkylphenate.

U.S. Pat. No. 6,677,281 discloses a lubricating composition containing ametal sulfonate, an ashless alkenyl succinimide and a borated polyolefindispersant.

U.S. Pat. No. 4,466,894 discloses a composition containing metal saltsof phosphorus thio-alcohols, a sulfurized phenate, and a benzotriazole.

International publication WO 93/03121 discloses a metal salt of at leastone of a sulfonate, a carboxylate and a phenate, in combination with analiphatic carboxylic acid or anhydride thereof.

It would be desirable for a low sulfur lubricating composition toprovide acceptable and/or improved anti-wear performance while alsoreducing and/or preventing deposit formation in the device beinglubricated. It would also be desirable to for a lubricating compositionto provide one or more of these improvements without negativelyimpacting any other performance areas, such as the demulsibility of thecomposition. The present invention provides a low sulfur lubricatingcomposition with such properties and also provides a method oflubricating a device using such compositions.

SUMMARY OF THE INVENTION

The invention provides a method for lubricating a mechanical devicerequiring industrial fluids, hydraulic fluids, turbine oils, circulatingoils, or combinations thereof, the method comprising: (I) supplying themechanical device with a lubricating composition comprising: (a) an oilof lubricating viscosity wherein the oil is substantially free ofsulfur; and (b) a friction modifier; resulting in reduced wear, reducedfriction, or combinations thereof within the device.

Component (a) may comprise a group II oil, a group III oil, agas-to-liquid oil, a poly-alpha-olefin, or combinations thereof. Thelubricating composition may further comprise a dispersant, anantioxidant, a corrosion inhibitor, a carboxylic acid or anhydride, adetergent, an antiwear agent, an antifoam, a metal deactivator, ademulsifier, a detergent stabilizer, or combinations thereof.

The invention further provides for the methods described above where thelubricating composition further comprises a metaldi-hydrocarbyl-substituted dithiophosphate, wherein at least onehydrocarbyl group is a branched primary hydrocarbyl group.

The invention further provides for the methods described above where thelubricating composition further comprises a metal-freedi-hydrocarbyl-substituted dithiophosphate, wherein at least onehydrocarbyl group is a branched primary hydrocarbyl group.

The invention further provides for the lubricating composition beingprepared by adding the friction modifiers described herein as anaftermarket treatment to the oil of lubricating viscosity and/or aformulated hydraulic fluid.

The invention also provides for a lubricating composition comprising:(a) an oil of lubricating viscosity wherein the oil is substantiallyfree of sulfur; (b) a friction modifier; (c) a dispersant; (d) a metaldi-hydrocarbyl-substituted dithiophosphate, wherein at least onehydrocarbyl group is a branched primary hydrocarbyl group; and (e)optionally a viscosity index improving polymer.

The invention also provides for a lubricating composition comprising:(a) an oil of lubricating viscosity wherein the oil is substantiallyfree of sulfur; (b) a friction modifier; (c) a metal-freedi-hydrocarbyl-substituted dithiophosphate, wherein at least onehydrocarbyl group is a branched primary hydrocarbyl group; (d) anantioxidant; and (e) optionally a viscosity index improving polymer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a lubricating composition and method asdefined above. As used herein the term ‘substantially free of’ withregards to water, means the lubricating composition contains not morethan contaminant amounts of water, for example, water present at lessthan about 1 wt %, preferably less than about 0.5 wt %, or even about0.2 wt % or less of the lubricating composition.

It should however be noted that during application of the lubricatingcomposition in industrial fluids, hydraulic fluids, turbine oils,circulating oils, or combinations thereof, extraneous water may beincorporated into the system. The extraneous water is not included inthe contaminant amounts of water disclosed above.

In one embodiment the lubricating composition is substantially free of,to the absence of water. In one embodiment the lubricating compositionis not an oil-in water emulsion.

In one embodiment the methods of the invention provide a means forimproving the antiwear performance (or wear performance) of a hydraulicfluid. In another embodiment the invention provides a means forimproving the antiwear performance of a low sulfur hydraulic fluidwithout adversely impacting the demulsibility of the fluid. In stillother embodiments, the invention provides a means for improving theantiwear performance of a low sulfur hydraulic fluid containing adispersant. In some of these embodiments the dispersant may containmetal, such as zinc. In each of the embodiments described above, thehydraulic fluids may be based on Group II or similar oils. Any of theembodiments described above may result in hydraulic fluid compositionswhich are zinc free, metal free, or ashless (i.e., does not containmetal in amounts greater than those associated with contaminantamounts). In still other embodiments, any of the embodiments describedabove may be free of viscosity modifiers, while in another set ofembodiments, any of embodiments described above may further comprise aviscosity modifier.

Oils of Lubricating Viscosity

The lubricating composition comprises an oil of lubricating viscosity.Such oils include natural and synthetic oils, oil derived fromhydro-cracking, hydrogenation, and hydro-finishing, unrefined, refinedand re-refined oils and mixtures thereof.

Unrefined oils are those obtained directly from a natural or syntheticsource generally without (or with little) further purificationtreatment.

Refined oils are similar to the unrefined oils except they have beenfurther treated in one or more purification steps to improve one or moreproperties. Purification techniques are known in the art and includesolvent extraction, distillation, acid or base extraction, filtration,percolation and the like.

Re-refined oils are also known as reclaimed or reprocessed oils, and areobtained by processes similar to those used to obtain refined oils andoften are additionally processed by techniques directed to removal ofspent additives and oil breakdown products.

Natural oils useful in making the inventive lubricants include animaloils, vegetable oils (e.g., castor oil, lard oil), mineral lubricatingoils such as liquid petroleum oils and solvent-treated or acid-treatedmineral lubricating oils of the paraffinic, naphthenic or mixedparaffinic-naphthenic types and oils derived from coal or shale ormixtures thereof.

Synthetic lubricating oils are useful and include hydrocarbon oils suchas polymerized and interpolymerized olefins (e.g., polybutylenes,polypropylenes, propylene isobutylene copolymers); poly(1-hexenes),poly(1-octenes), poly(1-decenes), and mixtures thereof; alkyl-benzenes(e.g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,di-(2-ethylhexyl)-benzenes); polyphenyls (e.g., biphenyls, terphenyls,alkylated polyphenyls); alkylated diphenyl ethers and alkylated diphenylsulfides and the derivatives, analogs and homologs thereof or mixturesthereof.

Other synthetic lubricating oils include liquid esters ofphosphorus-containing acids (e.g., tricresyl phosphate, trioctylphosphate, and the diethyl ester of decane phosphonic acid), andpolymeric tetrahydrofurans. Synthetic oils may be produced byFischer-Tropsch reactions and typically may be hydroisomerisedFischer-Tropsch hydrocarbons or waxes. In one embodiment oils may beprepared by a Fischer-Tropsch gas-to-liquid synthetic procedure as wellas other gas-to-liquid oils.

Oils of lubricating viscosity may also be defined as specified in theAmerican Petroleum Institute (API) Base Oil InterchangeabilityGuidelines. The five base oil groups are as follows: Group I (sulfurcontent>0.03 wt %, and/or <90 wt % saturates, viscosity index 80-120);Group II (sulfur content ≦0.03 wt %, and ≧90 wt % saturates, viscosityindex 80-120); Group III (sulfur content≦0.03 wt %, and ≧90 wt %saturates, viscosity index≧120); Group IV (all polyalphaolefins (PAOs));and Group V (all others not included in Groups I, II, III, or IV). Theoil of lubricating viscosity comprises an API Group I, Group II, GroupIII, Group IV, Group V oil or mixtures thereof. Often the oil oflubricating viscosity is an API Group I, Group II, Group III, Group IVoil or mixtures thereof. Alternatively the oil of lubricating viscosityis often an API Group I, Group II, Group III oil or mixtures thereof.

Oils suitable for use in the invention are substantially free of sulfur,which means that the oil component contains less than 3000 ppm ofsulfur, less than 1500 ppm of sulfur, or less than 1000 ppm of sulfur.In other embodiments, the oil component may contain less than 500 ppm ofsulfur, less than 300 ppm of sulfur, or less than 150 ppm of sulfur. Insome embodiments these limits on sulfur content may be applied to theoverall lubricating composition, which may include one or moreadditives.

Oils suitable for use in the invention may have (i) a sulfur content ofless than 0.03% wt, (ii) contain at least 90% wt saturates (iii) have aviscosity index of at least 120, or (iv) combinations thereof. In someembodiments individual oils used in the composition may not meet any ofthese requirements, but the total oil component, which may be a mixtureof two or more oils, does meet at least one of the requirementsdescribed. In some embodiments, the oils are Group II, Group III, orGroup IV oils. In other embodiments the compositions of the inventionare free of Group I oils. In still other embodiments the compositions ofthe invention contain less than 10% wt Group I oils.

The invention is focused on improving the wear properties of low sulfurhydraulic fluids. Hydraulic fluids containing Group I base oilstypically contain relatively high sulfur levels and so inherently havebetter wear properties such that the use of the invention is not needed.In contrast, low sulfur hydraulic fluids, such as those containing GroupII base oils and similar low sulfur oils, have worse wear properties.The compositions of the invention address this problem and improve thewear properties of such fluids. In some embodiments this improvement isachieved without negatively impacting the demulsibility of the fluid.

Oils of lubricating viscosity include natural or synthetic lubricatingoils and mixtures thereof. Natural oils include animal oils, minerallubricating oils, and solvent or acid treated mineral oils. Syntheticlubricating oils include hydrocarbon oils (polyalpha-olefins),halo-substituted hydrocarbon oils, alkylene oxide polymers, esters ofdicarboxylic acids and polyols, esters of phosphorus-containing acids,polymeric tetrahydrofurans and silicon-based oils. Preferably, the oilof lubricating viscosity is a hydro-treated mineral oil or a syntheticlubricating oil, such as a polyolefin. Examples of useful oils oflubricating viscosity include XHVI base stocks, such as 100N isomerizedwax base stock (0.01% sulfur/141 VI), 120N isomerized wax base stock(0.01% sulfur/149 VI), 170N isomerized wax base stock (0.01% sulfur/142VI), and 250N isomerized wax base stock (0.01% sulfur/146 VI); refinedbase stocks, such as 250N solvent refined paraffinic mineral oil (0.16%sulfur/89 VI), 200N solvent refined naphthenic mineral oil (0.2%sulfur/60 VI), 100N solvent refined/hydro-treated paraffinic mineral oil(0.01% sulfur/98 VI), 240N solvent refined/hydro-treated paraffinicmineral oil (0.01% sulfur/98 VI), 80N solvent refined/hydro-treatedparaffinic mineral oil (0.08% sulfur/127 VI), and 150N solventrefined/hydro-treated paraffinic mineral oil (0.17% sulfur/127 VI). Adescription of oils of lubricating viscosity occurs in U.S. Pat. No.4,582,618 (column 2, line 37 through column 3, line 63, inclusive).

In some embodiments the oil used in the compositions of the inventioninclude Chevron™ RLOP, Motiva™ Star and Petro Canada™ Group II oils, aswell as mixtures thereof. In other embodiments the oil has a sulfurcontent of 0 to 50 ppm and/or a viscosity index of up to 130. Suitableoils may be mixtures of two or more oils, including oils with differentsulfur contents, viscosity indexes, and our viscosities.

In one embodiment, the oil of lubricating viscosity is apolyalpha-olefin (PAO). Typically, the polyalpha-olefins are derivedfrom monomers having from 4 to 30, or from 4 to 20, or from 6 to 16carbon atoms. Examples of useful PAOs include those derived from decene.These PAOs may have a viscosity from 3 to 150, or from 4 to 100, or from4 to 8 cSt at 100° C. Examples of PAOs include 4 cSt polyolefins, 6 cStpolyolefins, 40 cSt polyolefins and 100 cSt polyalphaolefins.

In one embodiment, the lubricating composition contains an oil oflubricating viscosity which has an iodine value of less than 9. Iodinevalue is determined according to ASTM D-460. In one embodiment, the oilhas an iodine value less than 8, or less than 6, or less than 4.

In one embodiment, the oil of lubricating viscosity is selected toprovide lubricating compositions with a Kinematic viscosity (KV), asmeasured by D445, of at least 3.5 cSt, or at least 4.0 cSt at 100° C. Inone embodiment, the lubricating compositions have an SAE gear viscositygrade of at least SAE 75W. In other embodiments the lubricatingcompositions of the present invention have a KV of 30 to 60 cSt at 40 C,or 35 to 46 cSt at 40 C, or about 46 cSt at 40 C. Such embodiments mayalso have a viscosity index (VI) of 50 to 200, 50 to 150, 75 to 125, orabout 100.

The lubricating composition may also have a so-called multigrade ratingsuch as SAE 75W-80, 75W-90, 75W-140, 80W-90, 80W-140, 85W-90, or85W-140. Multigrade lubricants may include a viscosity improver which isformulated with the oil of lubricating viscosity to provide the abovelubricant grades. Useful viscosity improvers include but are not limitedto polyolefins, such as ethylene-propylene copolymers, or polybutylenerubbers, including hydrogenated rubbers, such as styrene-butadiene orstyrene-isoprene rubbers; or polyacrylates, including polymethacrylates.In one embodiment, the viscosity improver is a polyolefin orpolymethacrylate. Viscosity improvers available commercially includeAcryloid™ viscosity improvers previously available from Rohm & Haaswhich have been integrated into the Viscoplex™ family; Shellvis™ rubbersavailable from Shell Chemical; Trilene™ polymers, such as Trilene™CP-40, available commercially from Chemtura, and Lubrizol 3100 seriesand 8400 series polymers, such as Lubrizol® 3174 available from TheLubrizol Corporation. These additives, as well as additional additiveswhich may be used in the compositions of the invention, are described inmore detail in the sections below. In other embodiments the lubricatingcompositions of the present invention have a KV of 20 to 40 cSt at 40 C,or 25 to 35 cSt at 40 C, or about 32 cSt at 40 C. Such embodiments mayalso have a viscosity index (VI) of greater than 200, greater than 300,greater than 400, or about 425.

In still other embodiments, the lubricating compositions of the presentinvention may have a KV of 20 to 100 cSt at 40 C and a VI of 80 to 450or a KV of 25 to 55 100 cSt at 40 C and a VI of 140 to 180.

In one embodiment, the oil of lubricating viscosity includes at leastone ester of a dicarboxylic acid. Typically the esters containing from 4to 30, preferably from 6 to 24, or from 7 to 18 carbon atoms in eachester group. Here, as well as elsewhere, in the specification andclaims, the range and ratio limits may be combined. Examples ofdicarboxylic acids include glutaric, adipic, pimelic, suberic, azelaicand sebacic. Example of ester groups include hexyl, octyl, decyl,dodecyl and tridecyl ester groups. The ester groups include linear aswell as branched ester groups such as iso arrangements of the esteralkyl group. A particularly useful ester of a dicarboxylic acid isdiisodecyl azelate. In some embodiments the oil of lubricating viscosityis substantially free or even free of esters or any one or more of thespecific esters described above.

The oil of lubricating viscosity may be present in ranges from 60 to99.9 wt %, or from 65 to 95 wt %, or from 70 to 85 wt %. In otherembodiments the oil of lubricating viscosity is present from 90 to 99.9wt %, 95 to 99.9 wt %, or 98 to 99.5 wt %.

The lubricating composition may be in the form of a concentrate and/or afully formulated lubricant. If the lubricating composition of thepresent invention is in the form of a concentrate (which may be combinedwith additional oil to form, in whole or in part, a finished lubricant),the ratio of the additives (a) to (d) to the oil of lubricatingviscosity and/or to diluent oil include the ranges of about 1:99 toabout 99:1 by weight, or from about 80:20 to about 10:90 by weight.

Friction Modifier

The friction modifiers used in the methods and compositions of thepresent invention may include those additives generally known asfriction modifiers and/or lubricity aids. A useful list of suchadditives is included in U.S. Pat. No. 4,792,410. U.S. Pat. No.5,110,488 discloses metal salts of fatty acids and especially zincsalts, useful as friction modifiers. Fatty acids are also usefulfriction modifiers. A list of friction modifiers suitable for inventionincludes: (i) fatty phosphites and/or phosphonates; (ii) fatty acidamides; (iii) fatty epoxides; (iv) borated fatty epoxides; (v) fattyamines; (vi) glycerol esters; (vii) borated glycerol esters; (viii)alkoxylated fatty amines; (ix) borated alkoxylated fatty amines; (x)metal salts of fatty acids; (xi) sulfurized olefins; (xii) fattyimidazolines; (xiii) condensation products of carboxylic acids orequivalents and polyalkylene-polyamines; (xiv) metal salts of alkylsalicylates; (xv) amine salts of alkylphosphoric acids; (xvi) fattyesters; (xvii) condensation products of carboxylic acids or equivalentswith polyols and mixtures thereof.

Representatives of each of these types of friction modifiers are knownand are commercially available. For instance, (i) includes componentsgenerally of the formulas: (RO)₂PHO; (RO)(HO)PHO; and P(OR)(OR)(OR). Inthese structures, the term “R” is conventionally referred to as an alkylgroup but may also be hydrogen. It is, of course, possible that thealkyl group is actually alkenyl and thus the terms “alkyl” and“alkylated,” as used herein, will embrace other than saturated alkylgroups within the component. The component should have sufficienthydrocarbyl groups to render it substantially oleophilic. In someembodiments the hydrocarbyl groups are substantially un-branched. Manysuitable such components are available commercially and may besynthesized as described in U.S. Pat. No. 4,752,416. In some embodimentsthe component contains 8 to 24 carbon atoms in each of R groups. Inother embodiments the component may be a fatty phosphite containing 12to 22 carbon atoms in each of the fatty radicals, or 16 to 20 carbonatoms. In one embodiment the fatty phosphite can be formed from oleylgroups, thus having 18 carbon atoms in each fatty radical.

The (iv) borated fatty epoxides are known from Canadian Patent No.1,188,704. These oil-soluble boron-containing compositions are preparedby reacting, at a temperature from 80° C. to 250° C., boric acid orboron trioxide with at least one fatty epoxide having the formula:

wherein each of R¹, R², R³ and R⁴ is hydrogen or an aliphatic radical,or any two thereof together with the epoxy carbon atom or atoms to whichthey are attached, form a cyclic radical. The fatty epoxide preferablycontains at least 8 carbon atoms.

The borated fatty epoxides can be characterized by the method for theirpreparation which involves the reaction of two materials. Reagent A canbe boron trioxide or any of the various forms of boric acid includingmetaboric acid (HBO₂), orthoboric acid (H₃BO₃) and tetraboric acid(H₂B₄O₇). Boric acid, and especially orthoboric acid, is preferred.Reagent B can be at least one fatty epoxide having the above formula. Inthe formula, each of the R groups is most often hydrogen or an aliphaticradical with at least one being a hydrocarbyl or aliphatic radicalcontaining at least 6 carbon atoms. The molar ratio of reagent A toreagent B is generally 1:0.25 to 1:4. Ratios of 1:1 to 1:3 arepreferred, with about 1:2 being an especially preferred ratio. Theborated fatty epoxides can be prepared by merely blending the tworeagents and heating them at temperature of 80° to 250° C., preferably100° to 200° C., for a period of time sufficient for reaction to takeplace. If desired, the reaction may be effected in the presence of asubstantially inert, normally liquid organic diluent. During thereaction, water is evolved and may be removed by distillation.

The (iii) non-borated fatty epoxides, corresponding to “Reagent B”above, are also useful as friction modifiers.

Borated amines are generally known from U.S. Pat. No. 4,622,158. Boratedamine friction modifiers (including (ix) borated alkoxylated fattyamines) are conveniently prepared by the reaction of a boron compounds,as described above, with the corresponding amines. The amine can be asimple fatty amine or hydroxy containing tertiary amines. The boratedamines can be prepared by adding the boron reactant, as described above,to an amine reactant and heating the resulting mixture at a 50° to 300°C., preferably 100° C. to 250° C. or 130° C. to 180° C., with stirring.The reaction is continued until by-product water ceases to evolve fromthe reaction mixture indicating completion of the reaction.

Among the amines useful in preparing the borated amines are commercialalkoxylated fatty amines known by the trademark “ETHOMEEN” and availablefrom Akzo Nobel. Representative examples of these ETHOMEEN™ materials isETHOMEEN™ C/12 (bis[2-hydroxyethyl]-cocoamine); ETHOMEEN™ C/20(polyoxyethylene[10]cocoamine); ETHOMEEN™ S/12(bis[2-hydroxyethyl]soyamine); ETHOMEEN™ T/12(bis[2-hydroxyethyl]allow-amine); ETHOMEEN™ T/15(polyoxyethylene-[5]tallowamine); ETHOMEEN™ O/12(bis[2-hydroxyethyl]oleyl-amine); ETHOMEEN™ 18/12(bis[2-hydroxyethyl]octadecylamine); and ETHOMEEN™ 18/25(polyoxyethylene[15]octadecylamine). Fatty amines and ethoxylated fattyamines are also described in U.S. Pat. No. 4,741,848. Dihydroxyethyltallowamine (commercially sold as ENT-12™) is included in these types ofamines.

The (viii) alkoxylated fatty amines, and (v) fatty amines themselves(such as oleylamine and dihydroxyethyl tallowamine) are generally usefulas friction modifiers in this invention. Such amines are commerciallyavailable.

Both borated and unborated fatty acid esters of glycerol can be used asfriction modifiers. The (vii) borated fatty acid esters of glycerol areprepared by borating a fatty acid ester of glycerol with boric acid withremoval of the water of reaction. Preferably, there is sufficient boronpresent such that each boron will react with from 1.5 to 2.5 hydroxylgroups present in the reaction mixture. The reaction may be carried outat a temperature in the range of 60° C. to 135° C., in the absence orpresence of any suitable organic solvent such as methanol, benzene,xylenes, toluene, or oil.

The (vi) fatty acid esters of glycerol themselves can be prepared by avariety of methods well known in the art. Many of these esters, such asglycerol monooleate and glycerol tallowate, are manufactured on acommercial scale. The esters useful are oil-soluble and are preferablyprepared from C8 to C22 fatty acids or mixtures thereof such as arefound in natural products and as are described in greater detail below.Fatty acid monoesters of glycerol are preferred, although, mixtures ofmono- and diesters may be used. For example, commercial glycerolmonooleate may contain a mixture of 45% to 55% by weight monoester and55% to 45% diester.

Fatty acids can be used in preparing the above glycerol esters; they canalso be used in preparing their (x) metal salts, (ii) amides, and (xii)imidazolines, any of which can also be used as friction modifiers.Preferred fatty acids are those containing 10 to 24 carbon atoms, or 12to 18. The acids can be branched or straight-chain, saturated orunsaturated. In some embodiments the acids are straight-chain acids. Inother embodiments the acids are branched. Suitable acids includedecanoic, oleic, stearic, isostearic, palmitic, myristic, palmitoleic,linoleic, lauric, and linolenic acids, and the acids from the naturalproducts tallow, palm oil, olive oil, peanut oil, corn oil, coconut oiland Neat's foot oil. A particularly preferred acid is oleic acid.Preferred metal salts include zinc and calcium salts. Examples areoverbased calcium salts and basic oleic acid-zinc salt complexes, suchas zinc oleate, which can be represented by the general formulaZn₄Oleate₆O₁. Preferred amides are those prepared by condensation withammonia or with primary or secondary amines such as ethylamine anddiethanolamine. Fatty imidazolines are the cyclic condensation productof an acid with a diamine or polyamine such as a polyethylenepolyamine.The imidazolines are generally represented by the structure:

where R is an alkyl group and R′ is hydrogen or a hydrocarbyl group or asubstituted hydrocarbyl group, including —(CH₂CH₂NH)n— groups. In apreferred embodiment the friction modifier is the condensation productof a C10 to C24 fatty acid with a polyalkylene polyamine, and inparticular, the product of isostearic acid with tetraethylenepentamine.

The condensation products of carboxylic acids and polyalkyleneamines(xiii) may generally be imidazolines or amides. They may be derived fromany of the carboxylic acids described above and any of the polyaminesdescribed herein.

Sulfurized olefins (xi) are well known commercial materials used asfriction modifiers. A particularly preferred sulfurized olefin is onewhich is prepared in accordance with the detailed teachings of U.S. Pat.Nos. 4,957,651 and 4,959,168. Described therein is a co-sulfurizedmixture of 2 or more reactants selected from the group consisting of (1)at least one fatty acid ester of a polyhydric alcohol, (2) at least onefatty acid, (3) at least one olefin, and (4) at least one fatty acidester of a monohydric alcohol. Reactant (3), the olefin component,comprises at least one olefin. This olefin is preferably an aliphaticolefin, which usually will contain 4 to 40 carbon atoms, preferably from8 to 36 carbon atoms. Terminal olefins, or alpha-olefins, are preferred,especially those having from 12 to 20 carbon atoms. Mixtures of theseolefins are commercially available, and such mixtures are contemplatedfor use in this invention. The co-sulfurized mixture of two or more ofthe reactants, is prepared by reacting the mixture of appropriatereactants with a source of sulfur. The mixture to be sulfurized cancontain 10 to 90 parts of Reactant (1), or 0.1 to 15 parts by weight ofReactant (2); or 10 to 90 parts, often 15 to 60 parts, more often 25 to35 parts by weight of Reactant (3), or 10 to 90 parts by weight ofreactant (4). The mixture, in the present invention, includes Reactant(3) and at least one other member of the group of reactants identifiedas reactants (1), (2) and (4). The sulfurization reaction generally iseffected at an elevated temperature with agitation and optionally in aninert atmosphere and in the presence of an inert solvent. Thesulfurizing agents useful in the process of the present inventioninclude elemental sulfur, which is preferred, hydrogen sulfide, sulfurhalide plus sodium sulfide, and a mixture of hydrogen sulfide and sulfuror sulfur dioxide. Typically often 0.5 to 3 moles of sulfur are employedper mole of olefinic bonds. Sulfurized olefins may also includesulfurized oils such as vegetable oil, lard oil, oleic acid and olefinmixtures.

Metal salts of alkyl salicylates (xiv) include calcium and other saltsof long chain (e.g. C12 to C16) alkyl-substituted salicylic acids.

Amine salts of alkylphosphoric acids (xv) include salts of oleyl andother long chain esters of phosphoric acid, with amines as describedbelow. Useful amines in this regard are tertiary-aliphatic primaryamines, sold under the tradename Primene™.

In some embodiments the friction modifier is a fatty acid or fatty oil,a metal salt of a fatty acid, a fatty amide, a sulfurized fatty oil orfatty acid, an alkyl phosphate, an alkyl phosphate amine salt; acondensation product of a carboxylic acid and a polyamine, a boratedfatty epoxide, a fatty imidazoline, or combinations thereof.

In other embodiments the friction modifier may be the condensationproduct of isostearic acid and tetraethylene pentamine, the condensationproduct of isostearic acid and 1-[tris(hydroxymethyl)]methylamine,borated polytetradecyloxirane, zinc oleate, hydroxylethyl-2-heptadecenylimidazoline, dioleyl hydrogen phosphate, C14-C18 alkyl phosphate or theamine salt thereof, sulfurized vegetable oil, sulfurized lard oil,sulfurized oleic acid, sulfurized olefins, oleyl amide, glycerolmonooleate, soybean oil, or mixtures thereof.

In still other embodiments the friction modifier may be glycerolmonooleate, oleylamide, the reaction product of isostearic acid and2-amino-2-hydroxymethyl-1,3-propanediol, sorbitan monooleate,9-octadecenoic acid, isostearyl amide, isostearyl monooleate orcombinations thereof.

The amount of friction modifier may be 0.01 to 2 wt % or 0.03 to 1 wt %of the lubricating composition, and in some embodiments is 0.05 to 1.5wt %, 0.05 to 0.5 wt %, 0.08 to 1 wt %, or 0.075 to 0.3 wt %. In someembodiments, however, the amount of friction modifier is present at lessthan 0.5 percent or less than 0.2 percent by weight, or present from 0.2to 0.5 percent. In other embodiments the friction modifier is present atmore than 500 ppm, more than 1000 ppm, more than 1500 ppm or more than2000 ppm, but in each of these embodiments the upper limit may be nomore than 5000 ppm, no more than 3000 ppm, or no more than 2000 ppm.These ranges may apply to the amounts of individual friction modifierpresent in the composition or to the total friction modifier componentin the compositions, which may include a mixture of two or more frictionmodifiers.

Many friction modifiers tend to also act as emulsifiers. This is oftendue to the fact that friction modifiers often have non-polar fatty tailsand polar head groups. Emulsibility, or rather decreased demulsibility,is a result that is undesirable in hydraulic fluids, where it isdesirable for such compositions to remain separate from and not entrainany water with which the fluid may come into contact. The frictionmodifiers of the present invention may be used to improve the antiwearperformance of the hydraulic fluid, however in some embodiments caremust be taken to avoid using the friction modifier at a level that wouldnegatively impact the demulsibility of the fluid.

The compositions of the invention may further include additionaladditives or additive packages. Many of the additives which may be usedare described in greater detail below and these additives may be addedseparately or as an additive package. Additive packages may contain oneor more of the additives described herein and may also contain someamount of diluent oil and/or solvent. An additive package may be addedto the compositions of the invention such that they are present at 0.2to 4.0 wt %, 0.5 to 3.0 wt %, or 0.6 to 2.0 wt %.

Metal Containing Dispersant

The compositions of the invention may optionally contain a metalcontaining dispersant. The dispersant may be present in ranges from 0 to5 wt %, or from 0.05 to 2.5 wt %, or from 0.1 to 1.5 wt %. In differentembodiments the metal containing dispersant is present at 0.2 wt %, 0.3wt %, 0.5 wt %, 0.7 wt %, 0.9 wt %, or 1.1 wt %.

The metal of the metal containing dispersant comprises zinc, copper,magnesium, barium or calcium. In one embodiment the metal is zinc.

The dispersant may include N-substituted long chain alkenyl succinimidesor long chain alkenyl esters, partial esters or salts thereof.

Examples of N-substituted long chain alkenyl succinimides includepolyisobutylene succinimide with number average molecular weight of thepolyisobutylene substituent in the range about 350 to about 5000, orabout 500 to about 3000.

The long chain alkenyl esters, partial esters or salts thereof may beprepared by reacting an alkenyl substituted acylating agent (such as apolyisobutylene succinic acid) with a polyol.

Examples of a suitable polyol include ethylene glycol, propylene glycol,butylene glycol, pentaerythritol, mannitol, sorbitol, glycerol,di-glycerol, tri-glycerol, tetra-glycerol, erythritol,2-hydroxymethyl-2-methyl-1,3-propanediol (trimethylolethane),2-ethyl-2-(hydroxymethyl)-1,3-propanediol (trimethylolpropane),1,2,4-hexanetriol and mixtures thereof.

The succinimide may be prepared from a polyamine. Suitable polyaminesinclude alkylenediamine, a polyalkylenepolyamine such as apolyethylenepolyamine, or a mixture thereof. Useful examples ofpolyamines are ethylenediamine, propylenediamine, 1,3-diaminopropane,N-methylethylenediamine, diethylenetriamine, triethylenetetramine,tetraethylenepentamine, tris(2-aminoethyl)amine, andpolyethylenepolyamine bottoms (HPAX® amines commercially produced by DowChemicals).

In one embodiment the invention further comprises at least onedispersant derived from polyisobutenyl succinic anhydride, an amine andzinc oxide to form a polyisobutylene succinimide complex or salt with azinc compound or cation. The polyisobutylene succinimide complex withzinc may be used alone or in combination with other dispersants. Methodsof preparing polyisobutylene succinimide complex with zinc are describedin more detail in U.S. Pat. No. 3,636,603.

The compositions of the invention may also include non-metal containingdispersants. These dispersants can be the N-substituted long chainalkenyl succinimides or long chain alkenyl esters, partial estersthereof described above before the salt formation with the metal takesplace. Borated versions and/or other derivatives of any of thedispersants described above may also be used.

Metal Di-Hydrocarbyl Substituted Dithiophosphate

The compositions of the invention may further comprise a metaldihydrocarbyl dithiophosphate. Metal dihydrocarbyl dithiophosphatessuitable for use in the invention contain at least one branchedhydrocarbyl group. The hydrocarbyl dithiophosphate includes thoserepresented by the formula:

wherein M′ comprises a metal; and both R¹ and R² are hydrocarbyl groupsor mixtures thereof, with the proviso that at least one of R¹ and R² isa branched primary hydrocarbyl group, or mixtures thereof. In oneembodiment both R¹ and R² are branched primary hydrocarbyl groups.

Each branched hydrocarbyl group may contain about 3 to about 20, orabout 8 to about 16, or about 8 to about 14 carbon atoms. Examples of asuitable branched hydrocarbyl group include 2-ethylhexyl, iso-octyl,iso-nonyl, iso-decyl, iso-dodecyl, iso-pentadecyl, 2-methyl-1-pentyl,isobutyl, 2-propyl-1-decyl or mixtures thereof. In one embodiment thebranched hydrocarbyl group comprises at least one of 2-ethylhexyl,iso-nonyl, iso-decyl, or mixtures thereof.

When only one of R¹ and R² is branched, the non-branched group may belinear alkyl or aryl. In one embodiment both R¹ and R² are branched.

M′ is a metal, and n is an integer equal to the available valence of M′.M′ is mono- or di- or tri-valent, in one embodiment divalent and inanother embodiment a divalent transition metal. In one embodiment M′ iszinc. In one embodiment M′ is calcium. In one embodiment M′ is barium.Examples of a metal hydrocarbyl dithiophosphate include zincdihydrocarbyl dithiophosphates (often referred to as ZDDP, ZDP or ZDTP).

The metal dihydrocarbyl dithiophosphate may be present in thelubricating composition in ranges from about 0.01 to about 5 wt %, orfrom about 0.1 to about 2 wt %, or from about 0.2 to about 1 wt %. Indifferent embodiments the metal dihydrocarbyl dithiophosphate is presentat about 0.3 wt %, or about 0.5 wt %, or about 0.7 wt %, or about 0.9 wt%.

The compositions of the invention may also include non-metal containingdihydrocarbyl dithiophosphates. These additives can be dihydrocarbyldithiophosphate esters or partial esters thereof derived from thematerials described above before the salt formation with the metal takesplace. These additives include dithiophosphoric acid esters.

Additional Additives

The compositions may optionally comprise one or more additivescomprising a detergent, an antioxidant, a corrosion inhibitor, ormixtures thereof.

Detergents.

The lubricant composition optionally further comprises known neutral oroverbased detergents i.e. ones prepared by conventional processes knownin the art. Suitable detergent substrates include, phenates, sulfurcontaining phenates, sulfonate s, salixarates, salicylates, carboxylicacid, phosphorus acid, mono- and/or di-thiophosphoric acid, alkylphenol, sulfur coupled alkyl phenol compounds, or saligenins. Thedetergent may be natural or synthetic. In one embodiment the detergentis synthetic.

In one embodiment the detergent comprises a sulfonate detergent. Thesulfonate detergent may also have corrosion inhibitor properties.

The sulfonate detergent of the composition includes compoundsrepresented by the formula:

(R¹)_(k)-A-SO₃M  (I)

wherein each R¹ is a hydrocarbyl group in one embodiment containingabout 6 to about 40, or from about 8 to about 35, or from about 8 toabout 30 carbon atoms; A may be independently a cyclic or acyclicdivalent or multivalent hydrocarbon group and is typically aromatic; Mis hydrogen, a valence of a metal ion, an ammonium ion or mixturesthereof; and k is an integer of 0 to about 5, for example 0, 1, 2, 3, 4,5. In one embodiment k is 1, 2 or 3, in another embodiment 1 or 2 and inanother embodiment 2.

In one embodiment k is 1 and R¹ is a branched alkyl group with about 6to about 40 carbon atoms. In one embodiment k is 1 and R¹ is a linearalkyl group with about 6 to about 40 carbon atoms.

Examples of suitable R¹ linear alkyl group include octyl, nonyl, decyl,undecyl, dodecyl, pentadecyl, hexadecyl, eicosyl, or mixtures thereof.

When M is a valence of a metal ion, the metal may be monovalent,divalent, trivalent or mixtures of such metals. When monovalent, themetal M includes an alkali metal such as lithium, sodium, or potassium,and when divalent, the metal M includes an alkaline earth metal such asmagnesium, calcium or barium. In one embodiment the metal is an alkalineearth metal. In one embodiment the metal is calcium.

When A is cyclic hydrocarbon group, suitable groups include phenylene orthose with fused cyclic groups such as naphthylene, indenylene,indanylene, bicyclopentadienylene or mixtures thereof. In one embodimentA comprises a naphthalene ring.

In different embodiments the detergent is neutral or overbased. In oneembodiment the detergent is neutral.

Examples of a suitable detergent include at least one of calcium dinonylnaphthalene sulfonate, calcium didecyl naphthalene sulfonate, didodecylnaphthalene sulfonate, calcium dipentadecyl naphthalene sulfonate, ormixtures thereof. In one embodiment the detergent comprises neutral orslightly overbased calcium dinonyl naphthalene sulfonate, or mixturesthereof.

The detergent may be present in the lubricating composition in rangesfrom 0 to about 3 wt %, or from about 0.001 to about 1.5 wt %, or fromabout 0.01 to about 0.75 wt %. In different embodiments the detergentmay be present at about 0.08 wt %, or about 0.1 wt %, or about 0.2 wt %,or about 0.4 wt % or about 0.6 wt % of the lubricating composition.

Antioxidant.

Antioxidant compounds are known and include alkylated diphenylamines,hindered phenols, molybdenum dithiocarbamates, and mixtures thereof.Suitable antioxidants also include alkylated alpha-phenyl naphthylamines. Antioxidant compounds may be used alone or in combination withother antioxidants.

Hindered phenol antioxidants often contain a secondary butyl and/or atertiary butyl group as a sterically hindering group. The phenol groupis often further substituted with a hydrocarbyl group and/or a bridginggroup linking to a second aromatic group. Examples of suitable hinderedphenol antioxidants include 2,6-di-tert-butylphenol,4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol,4-propyl-2,6-di-tert-butylphenol, 4-butyl-2,6-di-tert-butylphenol, or2,6-di-tert-butylphenol. In one embodiment the hindered phenolantioxidant is an ester and may include, e.g., Irganox™ L-135 from Ciba.Suitable examples of molybdenum dithiocarbamates which may be used as anantioxidant include commercial materials sold under the trade names suchas Vanlube 822™ and Molyvan™ A from R. T. Vanderbilt Co., Ltd., andAdeka Sakura-Lube™ S-100, S-165 and S-600 from Asahi Denka Kogyo K. Kand mixtures thereof.

Suitable alkylated diphenylamines include bis-nonylated diphenylamine,nonyl diphenylamine, octyl diphenylamine, bis-octylated diphenylamine,di-isobutylated diphenylamine, bis-decylated diphenylamine, decyldiphenylamine, bis-styrenated dipenylamine (that is, bis-phenethylateddiphenylamine), styrenated dipenylamine (that is, phenethylateddiphenylamine), and mixtures thereof.

The antioxidant may be present in the lubricating composition in rangesfrom 0 to about 3 wt %, or from about 0.01 to about 1.5 wt %, or fromabout 0.05 to about 0.8 wt %.

Corrosion Inhibitor.

The lubricating composition optionally further comprises a corrosioninhibitor. Examples of a corrosion inhibitor include benzotriazoles,1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles,2-alkyldithiobenzothiazoles,2-(N,N-dialkyldithiocarbamoyl)benzothiazoles,2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles,2,5-bis(N,N-dialkyldithiocarbamoyl)-1,3,4-thiadiazoles,2-alkyldithio-5-mercapto thiadiazoles or mixtures thereof. In oneembodiment the corrosion inhibitor is benzotriazole. In one embodimentthe corrosion inhibitor is a 2,5-bis(alkyl-dithio)-1,3,4-thiadiazole.The corrosion inhibitor may be used alone or in combination with othercorrosion inhibitors.

Benzotriazoles may contain hydrocarbyl substitutions on at least one ofthe following ring positions 1- or 2- or 4- or 5- or 6- or 7-. Thehydrocarbyl groups may contain 1 to about 30, or 1 to about 15, or 1 toabout 7 carbon atoms. In one embodiment the corrosion inhibitor istolyltriazole. In one embodiment hydrocarbyl benzotriazoles substitutedat positions 4- or 5- or 6- or 7- can be further reacted with analdehyde and a secondary amine.

Examples of suitable hydrocarbyl benzotriazoles further reacted with analdehyde and a secondary amine includeN,N-bis(heptyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis(nonyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis(decyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis(undecyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis(dodecyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine andmixtures thereof. In one embodiment the corrosion inhibitor isN,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine.

In one embodiment, the corrosion inhibitor is2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles. The alkyl groups of2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles contains 1 to about 30, orabout 2 to about 25, or 4 to about 20, or about 6 to about 16 carbonatoms. Examples of suitable 2,5-bis(alkyl-dithio)-1,3,4-thiadiazolesinclude 2,5-bis(tert-octyldithio)-1,3,4-thiadiazole,2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole,2,5-bis(tert-decyldithio)-1,3,4-thiadiazole,2,5-bis(tert-undecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole, or mixtures thereof.

The corrosion inhibitor may be present in ranges from about 0 to about1.5, or from about 0.0003 to about 1.5, or from about 0.0005 to about0.5, or from about 0.001 to about 0.1 weight percent of the lubricatingcomposition.

Viscosity Modifier. The lubricating composition optionally furthercomprises a viscosity modifier. As used herein the term “(meth)acrylate”includes a methacrylate and/or an acrylate. Viscosity modifiers (oftenreferred to as viscosity index improvers) suitable for use in theinvention include polymeric materials including a styrene-butadienerubber, an olefin copolymer, a hydrogenated styrene-isoprene polymer, ahydrogenated radical isoprene polymer, a poly(meth)acrylic acid ester, apoly(alkylstyrene), an alkenylaryl conjugated-diene copolymer, an esterof maleic anhydride-styrene copolymer or mixtures thereof.

In some embodiments the viscosity modifier is a poly(meth)acrylic acidester, an olefin copolymer or mixtures thereof.

Poly(meth)acrylic acid ester viscosity modifiers include copolymers of(a) a (meth)acrylic acid ester containing 9 to 30 carbons in the estergroup, (b) a (meth)acrylic acid ester containing 7 to 12 carbons in theester group wherein the ester group contains a 2-(C₁₋₄alkyl)-substituent and optionally (c) at least one monomer including a(meth)acrylic acid ester containing from 2 to 8 carbon atoms in theester group and which is different from the (meth)acrylic acid estersused in (a) and (b) above. In one embodiment the (meth)acrylic acidesters is derived from a methacrylate.

Viscosity modifiers may be derived from an olefin copolymer. The olefincopolymer includes those with a backbone containing 2 to 4 differentolefin monomers, in one embodiment 2 to 3 different olefin monomers andin yet another embodiment 2 different olefin monomers. The olefinmonomers include 2 to 20, in one embodiment 2 to 10, in anotherembodiment 2 to 6 and in yet another embodiment 2 to 4 carbon atoms.

The olefin copolymer includes an ethylene monomer and at least one otherco-monomer derived from an alpha-olefin having the formula H₂C═CHR³,wherein R³ is a hydrocarbyl group, in one embodiment an alkyl radicalcontaining 1 to 18, 1 to 10, 1 to 6 or 1 to 3 carbon atoms. Thehydrocarbyl group includes an alkyl radical that has a straight chain, abranched chain or mixtures thereof.

Examples of suitable co-monomers include propylene, 1-butene, 1-hexene,1-octene, 4-methyl-1-pentene, 1-decene, 1-dodecene, 1-tridecene,1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene,1-nonadecene or mixtures thereof. The co-monomer may be 1-butene,propylene or mixtures thereof. Examples of olefin copolymers includeethylene-propylene and ethylene-1-butene copolymers and mixturesthereof.

The viscosity modifiers are present on an oil free basis at of 0 wt % to30 wt %, 0.1 wt % to 30 wt %, 1 wt % to 25 wt %, 3 wt % to 20 wt % or 5wt % to 12 wt % of the composition. In one embodiment the viscositymodifier is present. In one embodiment the viscosity modifier is absent.

Optionally the lubricating composition further comprises at least one ofrust inhibitors, foam inhibitors, demulsifiers, pour point depressantsor mixtures thereof. The total combined amount of foam inhibitors,demulsifiers, pour point depressants may range from 0 to about 10 wt %,or from 0 to about 5 wt %, or from about 0.0001 to about 1 wt % of thelubricating composition.

Rust inhibitors include amine salts of carboxylic acids, such asoctylamine octanoate, condensation products of dodecenyl succinic acidor anhydride or a fatty acid, such as oleic acid with a polyamine, e.g.a polyalkylene polyamine such as triethylenetetramine, and half estersof alkenyl succinic acids in which the alkenyl radical contains about 8to about 24 carbon atoms with alcohols such as polyglycols. Rustinhibitors also include neutral naphthalene sulfonates. The rustinhibitors can be used alone or in combination with other rustinhibitors.

Foam inhibitors including polyacrylates, such as copolymers of ethylacrylate and 2-ethylhexylacrylate, and optionally vinyl acetate;demulsifiers including polyglycol derivatives, trialkyl phosphates,polyethylene glycols, polyethylene oxides, polypropylene oxides,polyethers and (ethylene oxide-propylene oxide) polymers; pour pointdepressants including esters of maleic anhydride-styrene,poly(meth)acrylates, polyacrylates or polyacrylamides; may also be usedin the lubricant compositions of the invention.

In some embodiments the compositions of the invention may besubstantially free of, or free of, zinc, but may contain other metals.In other embodiments the compositions are substantially free of, or freeof, all metals such that they may be considered ashless.

INDUSTRIAL APPLICATION

The method and lubricating composition of the invention may be suitableindustrial fluids, hydraulic fluids, turbine oils, circulating oils, orcombinations thereof. In different embodiments the lubricatingcomposition is suitable for various mechanical devices includingindustrial systems, hydraulic systems or turbines. In one embodiment thelubricating composition is suitable for a hydraulic system.

In some embodiments the methods and compositions of the invention areused in a hydraulic pump. In one embodiment the pump is a hydraulicpiston pump. In one embodiment the pump is a vane pump. In anotherembodiment the pump is a hydraulic hybrid piston and vane pump.

In one set of embodiments the hydraulic fluid of the invention containsa Group II oil, at least one friction modifier as described above (suchas a fatty acid ester), and an additive package containing a zinccontaining dispersant, at least one antioxidant, at least one antiwearadditive, an antifoam agent, a corrosion inhibitor, and a metaldeactivator. Such additive packages may be present at any of the rangesdescribed above, or at 0.8 to 2 wt %. In these embodiments, thehydraulic fluid is a zinc containing monograde formulation.

In another set of embodiments the hydraulic fluid of the inventioncontains a Group II oil, at least one friction modifier as describedabove (such as a fatty acid ester), and an additive package containing aviscosity modifier, at least one antioxidant, an antifoam agent, anantiwear agent, a corrosion inhibitor, and a metal deactivator. Suchadditive packages may be present at any of the ranges described above,or at 0.4 to 1.5 wt %. In such embodiments, the hydraulic fluid is anashless/zinc-free multigrade formulation.

EXAMPLES

The following examples provide an illustration of the invention. Theseexamples are non exhaustive and are not intended to limit the scope ofthe invention.

Piston Pump Testing Comparative Example 1

A hydraulic fluid composition is prepared by adding Additive Package Ato Petro Canada™ Group II oil at a level of 1.62 wt %. Additive PackageA contains a zinc containing dispersant derived from polyisobutylenesuccinic anhydride, a dialkyldiphenylamine antioxidant, a hinderedphenol antioxidant, a zinc dialkyl dithiophosphate, an antifoam agent, acorrosion inhibitor, and a metal deactivator. Petro Canada™ Group II oilis essentially sulfur free.

Comparative Example 2

A hydraulic fluid composition is prepared by adding Additive Package Bto ExxonMobil™ Esso Asia Pacific/Europe Group I oil at a level of 0.85wt %. Additive Package B contains a polyisobutylene succinic anhydridedispersant, an alkyl phenol antioxidant, a zinc alkyl dithiophosphateantioxidant, a detergent, an antifoam agent, a metal deactivator, acorrosion inhibitor, and a demulsifier. ExxonMobil™ Esso AsiaPacific/Europe Group I oil has a sulfur content of 3500-4000 ppm.

Comparative Example 3

A hydraulic fluid composition is prepared according to the procedure ofComparative Example 2 except that the ExxonMobil™ Esso AsiaPacific/Europe Group I oil is replaced with Petro Canada™ Group II oil.Petro Canada™ Group II oil is essentially sulfur free.

Example 1

A hydraulic fluid composition is prepared by adding 5000 ppm of glycerolmonooleate to Motiva™ Star Group II oil. No other additives are added.Motiva™ Star Group II oil contains about 9 ppm sulfur.

Example 2

A hydraulic fluid composition is prepared by adding 1000 ppm of glycerolmonooleate to Motiva™ Star Group II oil. No other additives are added.

Example 3

A hydraulic fluid composition is prepared by adding 500 ppm of glycerolmonooleate to the composition of Comparative Example 1.

Example 4

A hydraulic fluid is prepared by adding 1000 ppm of glycerol monooleateto the composition of Comparative Example 1.

Example 5

A hydraulic fluid is prepared by adding 1000 ppm of the condensationproduct of isostearic acid and tetraethylene pentamine to thecomposition of Comparative Example 1.

Example 6

A hydraulic fluid is prepared by adding 1000 ppm of oleyl amide to thecomposition of Comparative Example 1.

The examples and baselines of non-additized Group I and Group II oilsare tested in a piston pump screening test intended to correlate toParker Denison procedure A-TP-30533, published by Parker DenisonHydraulics.

The test method utilizes a standard piston pump operated at 4000 psi,and 140° C. for 24 hours. The baselines tested are the ExxonMobil™ GroupI oil used in Comparative Example 3 which has a sulfur content of3500-4000 ppm and Petro Canada™ Group II oil, which is essentiallysulfur free. The testing is carried out. The results of the testing aresummarized in the table below. Where repeats are completed both resultsare reported.

TABLE 1 Piston Pump Screen Testing Test Result¹ Example ID Total PistonLoss (mg) Group I Oil Baseline 427-FAIL Group II Oil Baseline 3342-FAILComparative Example 1 645-FAIL and 2338-FAIL² Comparative Example 224-PASS Comparative Example 3 403-FAIL Example 1 62-PASS Example 2136-PASS Example 3 406-FAIL³ Example 4 43-PASS Example 5 285-PASSExample 6 224-PASS ¹A passing result in this test is a total pistonweight loss of 300 mg or less. ²The difference in the failing resultsfor comparative example 1 is not unusual as the test measures the wearon the piston pump surfaces after the test. A failing test causes partwear that often deteriorates quickly once passing the 300 mg failurelimit. ³Example 3 uses the same base oil and additive package asComparative Example 1. While the result is still a fail, Example 3 showsan improvement in the wear test result over Comparative Example 1.

The results show the significant difference in wear performance of GroupI based and Group II based hydraulic fluids and the need for improvedwear performance in Group II based fluids and fluids with similar sulfurcontents. Group I based hydraulic fluids have significantly better wearproperties presumably due to their high sulfur contents as demonstratedby Comparative Example 2. As various environmental and regularity limitsresult in the reduction of base oil sulfur levels, and the move to moreGroup II based and similar hydraulic fluid, antiwear performance becomesmore of an issue.

The results also show that the addition of a friction modifier, such asglycerol monooleate, can significantly improve the antiwear performance(reduce the wear) delivered by a hydraulic fluid.

Demulsibility Testing Example 7

A hydraulic fluid composition is prepared by adding Additive Package A,as described in Comparative Example 1 above, to Motiva Star Group II oilat a level of 1.62 wt %. The fluid is then divided into three portionsand each is treated with a different level of glycerol monooleate, oneat 500 ppm, one at 1000 ppm, and one at 5000 ppm.

Example 8

A hydraulic fluid composition is prepared by adding Additive Package A,as described in Comparative Example 1 above, to Motiva Star Group II oilat a level of 1.62 wt %. The fluid is then divided into three portionsand each is treated with a different level of the condensation productof isostearic acid and tetraethylene pentamine, one at 500 ppm, one at1000 ppm, and one at 5000 ppm.

Example 9

A set of hydraulic fluid compositions are prepared according to Example8 except that Additive Package A is present at a level of 1.42 wt % andthe individual samples are treated with the friction modifier at 500ppm, 1000 ppm, and 2500 ppm.

Example 10

A set of hydraulic fluid compositions are prepared according to Example9 except the friction modifier is hydroxyethyl-2-heptadecenylimidazoline.

Example 11

A set of hydraulic fluid compositions are prepared according to Example9 except the friction modifier is dioleyl hydrogen phosphite.

Example 12

A set of hydraulic fluid compositions are prepared according to Example9 except the friction modifier is oleyl amide.

Example 13

A set of hydraulic fluid compositions are prepared according to Example9 except the friction modifier is C14-C18 alkyl phosphate amine salt andthe individual samples are treated with the friction modifier at 500ppm, and 1000 ppm.

Example 14

A set of hydraulic fluids are prepared according to Example 13 exceptthe friction modifier is tallow amine-2-ethoxylate.

Example 15

A set of hydraulic fluids are prepared according to Example 9 exceptthat a modified version of Additive Package A is used which is identicalto Additive Package A described above except that it contains a smalleramount of zinc dialkyl dithiophosphate and also contains a small amountof polyisobutylene succinic anhydride. All of the samples are toptreated with 40 ppm of a polyether demulsifier and the friction modifierused is glycerol monooleate. The individual samples are treated with thefriction modifier at 1000 ppm, 1500 ppm, 2000 ppm and 3000 ppm.

Example 16

A set of hydraulic fluids are prepared according to Example 15 exceptthat the polyether demulsifier is present in all samples at 100 ppm.

The Examples are tested to evaluate their demulsibility properties.Samples were tested according to ASTM D1401 water separation testprotocol, with tests of 80 mL samples carried out at 54.4° C. andresults reported as a series of numbers: XX-YY-ZZ (min), with the firstnumber (XX) representing the amount of oil phase, the second number (YY)representing the amount of water phase, and the third number (ZZ)representing the amount of any emulsion phase present. These values aremL readings of the 80 mL test sample. The final number in parenthesis isthe time in minutes when the readings were taken. The reading of asample is taken after mixing when complete separation of the water andoil phases occurs and no emulsion phase is present; however, if an anyamount of emulsion phase is still present at 15 minutes, the reportedreading is taken when 3 ml or less of an emulsion phase is present; ifthere is still more than 3 ml of emulsion phase at 30 minutes, thereading is taken at 30 minutes and the test is ended. The sampleformulations and test results are summarized in the tables below. TheSample ID provides information on the formulation tested and identify ofthe friction modifier (FM) present. The columns then show results atvarious treatment levels of the friction modifier. Several samples wererepeated. Where repeats were completed both readings are reported in thetable below.

TABLE 2 Demulsibility Testing FM at FM at FM at FM at FM at Sample ID 0ppm 500 ppm 1000 ppm 2500 ppm 5000 ppm Ex 7  40-40-00 (15) 39-40-01 (15)40-40-00 (10) 01-19-60 (30) 38-39-03 (25) Ex 8  40-40-00 (15) 01-00-79(30) 03-00-77 (30) 12-00-68 (30) Ex 9  39-39-02 (20) 39-39-02 (15)40-40-00 (30) 40-40-00 (20) Ex 10 42-38-00 (05) 41-39-00 (05) 40-40-00(15) Ex 11 41-38-01 (05) 40-40-00 (10) 00-06-74 (30) Ex 12 40-40-00 (10)40-40-00 (15) 39-40-01 (30) 40-40-00 (30) Ex 13 01-00-79 (30) 01-07-72(30) Ex 14 30-20-30 (30) 32-23-25 (30)

TABLE 3 Demulsibility Testing Sample FM at FM at FM at FM at ID 1000 ppm1500 ppm 2000 ppm 3000 ppm Ex 15 42-38-00 (10) 43-37-00 (25) 43-37-00(20) 25-34-31 (30) Ex 16 14-29-37 (30) 43-37-00 (30) 43-37-00 (25)11-33-36 (30)

The results show that the compositions of the present invention haveacceptable demulsibility properties at various treat rates of variousfriction modifiers. The methods and compositions of the inventionprovide improved wear performance while maintaining acceptabledemulsibility properties.

In this specification the terms “hydrocarbyl substituent” or“hydrocarbyl group,” as used herein are used in its ordinary sense,which is well-known to those skilled in the art. Specifically, it refersto a group primarily composed of carbon and hydrogen atoms and isattached to the remainder of the molecule through a carbon atom and doesnot exclude the presence of other atoms or groups in a proportioninsufficient to detract from the molecule having a predominantlyhydrocarbon character. In general, no more than two, preferably no morethan one, non-hydrocarbon substituent will be present for every tencarbon atoms in the hydrocarbyl group; typically, there will be nonon-hydrocarbon substituents in the hydrocarbyl group. A more detaileddefinition of the terms “hydrocarbyl substituent” or “hydrocarbylgroup,” is described in U.S. Pat. No. 6,583,092.

Each of the documents referred to above is incorporated herein byreference. Except in the Examples, or where otherwise explicitlyindicated, all numerical quantities in this description specifyingamounts of materials, reaction conditions, molecular weights, number ofcarbon atoms, and the like, are to be understood as modified by the word“about”. Unless otherwise indicated all percent values on weightpercents and all ppm values are on a weight to weight basis. Unlessotherwise indicated, each chemical or composition referred to hereinshould be interpreted as being a commercial grade material which maycontain the isomers, by-products, derivatives, and other such materialswhich are normally understood to be present in the commercial grade.However, the amount of each chemical component is presented exclusive ofany solvent or diluent, which may be customarily present in thecommercial material, unless otherwise indicated. It is to be understoodthat the upper and lower amount, range, and ratio limits set forthherein may be independently combined. Similarly, the ranges and amountsfor each element of the invention can be used together with ranges oramounts for any of the other elements. As used herein, the expression“consisting essentially of” permits the inclusion of substances that donot materially affect the basic and novel characteristics of thecomposition under consideration.

While the invention has been explained in relation to its preferredembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications as fall withinthe scope of the appended claims.

1. A method for lubricating a mechanical device requiring industrialfluids, hydraulic fluids, turbine oils, circulating oils, orcombinations thereof, the method comprising: I. supplying the mechanicaldevice with a lubricating composition comprising: (a) an oil oflubricating viscosity wherein the oil is substantially free of sulfur;and (b) a friction modifier; resulting in reduced wear, reducedfriction, or combinations thereof within the device.
 2. The method ofclaim 1 wherein component (a) comprises a group II oil, a group III oil,a gas-to-liquid oil, a poly-alpha-olefin, or combinations thereof,wherein component (a) has a sulfur content of less than 1000 ppm.
 3. Themethod of claim 1 wherein the lubricating composition further comprisesa dispersant, an antioxidant, a corrosion inhibitor, a carboxylic acidor anhydride, or combinations thereof.
 4. The method of claim 1 whereinthe lubricating composition further comprises a detergent, an antiwearagent, an antifoam, a metal deactivator, a demulsifier, a detergentstabilizer, or combinations thereof.
 5. The method of claim 1 whereinthe lubricating composition further comprises a metaldi-hydrocarbyl-substituted dithiophosphate, wherein at least onehydrocarbyl group is a branched primary hydrocarbyl group.
 6. The methodof claim 1 wherein the lubricating composition further comprises ametal-free di-hydrocarbyl-substituted dithiophosphate, wherein at leastone hydrocarbyl group is a branched primary hydrocarbyl group
 7. Themethod of claim 1 wherein the mechanical device is a hydraulic system.8. The method of claim 1 wherein component (b) comprises a fattyphosphite, a fatty acid amide, a fatty amine, a fatty acid, a fattyester, a condensation product of a carboxylic acid or equivalent with apolyalkylene-polyamine and/or a polyol, a borated fatty amine, a boratedfatty epoxide, a glycerol ester, a borated glycerol ester, a fattyimidazoline, a fatty oxazoline, a metal carboxylate, or combinations oftwo or more thereof.
 9. The method of claim 1 wherein the amount offriction modifier in the lubricating composition is 0.03 to 1 wt % andwherein the method further results in improved demulsibility of thelubricating composition with water.
 10. The method of claim 1 whereinthe lubricating composition is prepared by adding the friction modifieras an aftermarket treatment to the oil of lubricating viscosity.
 11. Alubricating composition comprising: (a) an oil of lubricating viscositywherein the oil is substantially free of sulfur; (b) a frictionmodifier; (c) a dispersant; (d) a metal di-hydrocarbyl-substituteddithiophosphate, wherein at least one hydrocarbyl group is a branchedprimary hydrocarbyl group; and (e) optionally a viscosity indeximproving polymer.
 12. A lubricating composition comprising: (a) an oilof lubricating viscosity wherein the oil is substantially free ofsulfur; (b) a friction modifier; (c) a metal-freedi-hydrocarbyl-substituted dithiophosphate, wherein at least onehydrocarbyl group is a branched primary hydrocarbyl group; (d) anantioxidant; and (e) optionally a viscosity index improving polymer 13.The composition of claim 11 wherein component (c) comprises a metalcontaining dispersant.
 14. The composition of claim 11 wherein component(e) is a polymethacrylates polymer.
 15. The composition of claim 11wherein component (c) comprises a metal-free dispersant.